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1.
纪松岗  梁东升 《分析化学》1998,26(11):1388-1390
采用SFE-MECC法分离测定大黄中的芦荟大黄素,大黄素和大黄素。萃取条件为压力41.4MPa,温度50℃,改性剂量0.4mL。被测组分在10min得到全部分离。本法准确,简便,快速,结果令人满意。  相似文献   

2.
研究了含汞三金属化合物[η_5-RC_5H_4(CO)_3M]_2Hg(M=Mo,W;R=Me,Et,CO_2Me,CO_2Et)与锌粉的置换反应,发现当取代基R为给电子的Me和Et时底物不发生反应,而取代基R为拉电子的CO_2Me和CO_2Et时,则底物中的汞可被锌置换,生成带有机官能团的三金属化合物[η_5-RC_5H_4(CO)_3M]_2Zn;另外,还发现R为CO_2Et,M为Mo的产物[η_5-RC_5H_4(CO)_3M]_2Zn可在室温下被分解为相应的氯代物η_5-EtO_2CC_5H_4MoCl.  相似文献   

3.
通过η5-R~1C_5H_4(CO)_3MNa与η~5-R~2C_5H_4(CO)_3MNa(M=Mo,W)以及η~5-R~1C_5H_4(CO)_3MoNa与η~5-R~2C_5H_4(CO)_3WNa在Fe_2(SO_4)_3醋酸水溶液作用下的交叉氧化偶联反应,合成了7个新的非对称型金属单键化合物η~5-R~1C_5H_4(CO)-3Mo─Mo(CO)_3C_5H_4R~2-η~5(R~1,R~2:C(O)Me,CO2Et),η5-R1C5N4(CO)3W─W(CO)3C5H4R2-η5(R1,R2:C(O)Me,CO2Et;H,CO2Et)和η5-R1C5H4(CO)3Mo─W(CO)3C5H4R2-η5(R1,R2:C(O)Me,H;Et,C(O)Me;C(O)Me,n-Bu;CO2Me,n-Bu).用C/N分析、IR、1HNMR和MS表征了它们的结构,并对该氧化偶联反应的特点进行了讨论.  相似文献   

4.
研究用烃橡胶(SBR、PB)和聚二甲基硅氧烷(PDMS)分散α,ω-对乙氧羰氧基苯甲酸聚乙二醇酯(PEECB)而得到聚合物分散液晶复合膜(PDLCM).用这种复合膜进行富氧分离,当PEECB-4.05(4.05为聚醚软段的数均聚合度DP)的含量超过某一临界值(约23.0%wt)时,室温下SBR/PEECB-4.05/PDMS体系膜的氧气透过系数Po2值达70~634barrer),增加约60倍,分离系数仍较高(αo2/N2=3.47~2.59).考察了各种影响因素对膜透气性能的影响.  相似文献   

5.
STUDYONREDUCTIONMECHANiSMOF1,5-DIAMINO-4.8-DIHYDROXYANTHRAQUINONEELECTROLYSISChunAnMA(ChemicalEngineeringDepartment,ZhejiangU...  相似文献   

6.
用IR、DSC、WAXD、正交偏光显微镜、SEM、TEM等手段,表征了所合成的液晶/烃橡胶、硅橡胶三元共混复合膜的织态结构及液晶态转变,结果发现,液晶PEECB-4.05由于与SBR和PDMS共混,Tk-s转变温度下降了37.5℃,体系存在不完全的相分离,液晶PEECB-4.05在体系中形成液晶富集区(LC-rich domain),大小约0.2-2.2μm,在压力的作用下,连续的液晶富集区形成宽  相似文献   

7.
纳米尖晶石型Co2MnO4的形成过程及其F-T反应性能   总被引:2,自引:0,他引:2  
梁琦 《催化学报》1998,19(1):33-36
用溶胶凝胶法制备了尖晶石型Co2MnO4超细粒子,用DTATG,XRD,TEM,FTIR等手段研究了Co2MnO4超细粒子的形成过程,进而用反应评价结合XRD,XPS,BET比表面积测试研究了Co2MnO4催化剂的比表面积和表面结构与其FT反应性能间的关系.结果表明,Co2MnO4超细粒子可以在较低温度(250~350℃)下形成,并具有粒度小,分布均匀等特点.用该法制备的超细粒子Co2MnO4,其催化活性明显优于相同组成的大颗粒催化剂.  相似文献   

8.
用IR、DSC、WAXD、正交偏光显微镜、SEM、TEM等手段,表征了所合成的液晶/烃橡胶/硅橡胶三元共混复合膜的织态结构及液晶态转变.结果发现,液晶PEECB—4.05由于与SBR和PDMS共混,Tk-s转变温度下降了37.5℃,体系存在不完全的相分离.液晶PEECB—4.05在体系中形成液晶富集区(LC—richdomain),大小约02—2.2μm不等.在压力的作用下,连续的液晶富集区形成宽约7.0μm并垂直于膜的平面的通道.这些结果是第Ⅰ报中这类富氧膜透气率产生突变的根本原因.  相似文献   

9.
本文以聚四氟乙烯(PTEE)悬浮体为氟化剂,对悬浮体制样ETV-ICP-AES直接测定生物试样中不同挥发性元素钼、铜和镉的蒸发行为,影响因素及分析性能进行了比较研究,得出了相应的规律性。在选定实验条件下,本法测定Mo,Cu和Cd的检出限分别为0.43、4.2和141ng/mL,RSD分别为3.8%、4.2%和2.2%。提出的方法已应用于CRM281生物标样分析,结果与参考值吻合。  相似文献   

10.
脱氧核糖核酸变性和损伤的吸附伏安法研究   总被引:2,自引:0,他引:2  
陆宗鹏  卢莠芬 《分析化学》1996,24(4):463-466
本文用汞电极(HMDE)二次导数阴极吸附伏安(SD-AdCSV)和碳电极(GCE、CPE)导数循环伏安(FD-CV)法研究了核酸受热、紫外线、超声波和丝裂霉素C(MMC)作用下的变性作用。在0.1mol/L(K2HPO4+KH2PO4)-0.1mol.L NaCl(pH7.0)底液中,吸附的单股(ss-)和双螺旋(ds-)DNA分别在HMDE上得到特征还原峰P3和P2,和在碳电极上得到氧化峰A。物  相似文献   

11.
多环芳二酐型聚酯亚胺膜的透气性能李悦生,丁孟贤,徐纪平(浙江大学高分子科学与工程研究所,杭州,310027)(中国科学院长春应用化学研究所)关键词聚醚酰亚胺,聚酯酰亚胺,膜,透气性通常的聚酰亚胺加工性能较差,在芳环二酐的苯环间引入醚键等柔性基团后,其...  相似文献   

12.
A QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of benazolin-ethyl and quizalofop-p-ethyl in rape and soil by high-performance liquid chromatography-tandem mass spectrometry has been developed in this study. The residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil were determined with the developed method. The half-lives of benazolin-ethyl in rape straw and soil were 3.7–5.1 days and 14.3–26.3 days, respectively. The half-lives of quizalofop-p-ethyl in rape straw and soil were 5.0-6.1 days and 0.3–9.7 days, respectively. The residue of benazolin-ethyl and quizalofop-p-ethyl in rapeseed and soil were below the detection limit (i.e., 0.5?mg?kg?1, the maximum residue level of European Union for quizalofop-p-ethyl).  相似文献   

13.
微量元素与疾病诊断治疗的研究现状及展望   总被引:8,自引:0,他引:8  
对国内外微量元素与疾病的关系及其诊断治疗的研究现状及研究动向进行了综述,包括:微量元素与地方病、癌肿、心血管病、糖尿病、眼病、神经系统病等。参考文献72篇。  相似文献   

14.
15.
In this work, ferrocene- and ferrocenium-containing salts were employed to modify montmorillonite. X-ray measurements show an increase in the interlayer spacing upon clay modification, which means that the larger and more organophilic cations were inserted into the gallery space of montmorillonite. Attempts to prepare nanocomposites of polystyrene and ethylene vinyl acetate copolymers lead to immiscible systems; the morphology of these systems was elucidated with TEM, XRD and cone calorimetry. The thermal stability of the composites is greater than that of the virgin polymer.  相似文献   

16.
朱劲波  马立群  梁飞  苗迎春  王立民 《应用化学》2015,32(11):1221-1230
Ti-V基储氢合金在室温、常压下即可表现出良好的储氢特性,且质量储氢容量明显高于传统AB5型储氢合金,从而在氢气的精制和回收、运输和储存及热泵等方面有较早的应用。 此外,在混合气体分离、核反应堆中处理氢的同位素、镍氢电池及燃料电池负极材料等方面也得到了广泛的研究与关注。 基于目前Ti-V基储氢合金的研究现状,概述了该类合金的优势、限制性因素(包括成因)及改性手段。 此外,为了进一步理解Ti-V基合金储氢机理、构建合金组分与储氢特性之间的对应关系,本工作重点围绕Ti-V基储氢合金及其氢化物的结构、组分优化设计展开综述,并对其未来研究方向做出展望。  相似文献   

17.
钒与糖代谢及糖尿病   总被引:1,自引:0,他引:1  
微量元素钒作为生物体内必需元素,经证实有很重要的生理学功能,与机体糖代谢有十分密切的关系,且能降低糖尿病动物模型的高血糖,极有可能被开发为治疗糖尿病的药物。  相似文献   

18.
Herein, we present the synthetic route and the photophysical, electrochemical as well as laser properties of novel red‐emitting boron‐dipyrromethenes (BODIPYs) bearing arylethyne moieties. Such functionality is added along the main axis of the chromophore leading to single‐ and double‐substituted derivatives. The relationship between the dye structure and the lasing properties is studied in detail with the help of the photophysical and electrochemical properties as well as quantum mechanical simulations. The asymmetric substitution of the parent dye induces inhomogeneities in the charge distribution, which leads to an overall loss of the fluorescence capacity, mainly in polar media. Such non‐radiative deactivation processes can be softened by decreasing the electron‐donor ability of the substituent or even avoided by symmetrical substitution. Thus, grafting of the arylethyne moieties at the longitudinal axis of the indacene core results in an effective strategy to develop red‐edge BODIPYs with highly efficient and photostable laser emission.  相似文献   

19.
The monomeric ν(N—H) vibrations of various trisubstituted ureas of the R2UPh type and -thioureas of the R2TUPh type have been studied. The trans—out isomerism in the former and the trans—out—cis isomerism in the latter are discussed from the point of view of steric effect. The monomeric ν(N—H) vibrations of RPhUPh and RPhTUPh are also examined. The single band appearing in the spectrum of both ureas is characteristic of the cis form; this suggests the existence of phenyl—phenyl interaction (the stacking interaction proposed by Galabov et al. [10]). Behavior of ν(N—H) vibrations at several concentrations is shown to be clearly different in the three forms (trans, out and cis). The presence of the cis form is confirmed by solvent effect experiments.  相似文献   

20.
王修然  万宝玉  胡继萍 《合成化学》2001,9(5):452-454,468
三茂基镧系化合物和苯并三氮唑在四氢呋喃中反应,合成了7个未见文献报道的含茂基苯并三氮唑基镧系有机配合物,经元素分析、IR和MS测定,从有关数据推测了这类配合物的可能结构。  相似文献   

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